Roller swaging of hydraulic tubing as a method of attaching fittings is a common practice in the aerospace industry. To roller swage a fitting to a tube, the end of a mandrel and roller swaging assembly expander assembly is inserted into the tube and a fitting to be swaged onto the tube is placed on the tube. The end of the expander assembly swage rollers expand outward and inward according to the axial position of the mandrel. The rotating tapered mandrel is moved along the axis of the expander assembly and frictionally engages the rollers and forces the rollers against the inner wall of the tube. The mandrel continues to rotate and move axially to expand the roller working diameter forcing tube material to flow into grooves in the fitting to produce a strong sealed connection between the tube and the fitting.
The rollers that support the mandrel through a support cage are tapered or can be angled so that their rotational axis is at a relative angle to the rotational axis of the mandrel which produces an axial force on the mandrel as it is rotated. The mandrel moves axially inward when the mandrel is rotated in one direction and the mandrel moves axially outward when the mandrel is rotated in an opposite direction. This prevents custom swaging since the swage rollers cannot be held and rotated in one axial position since they start axially moving as soon as the mandrel is rotated. Also, burnishing is not possible using this prior art device.
As part of the swaging process, the inside diameter of the tube is checked after swaging to confirm that specifications are satisfied. This prior art process adds significant time because the operator must remove the swaged assembly from the swaging machine and then make the measurement using a micrometer to confirm that the inside diameter of the tube meets specifications for a good quality swage. If the measurements do not meet the specifications, then the piece must be re-worked or discarded.